The new command line option --sql-target-config lets you specify a file that looks like:
db=YOURDB
user=YOURUSER
passwd=YOURPASS
match_query=YOURQUERY
When someone connects to the proxy it will make a database connetion and run the query you specify to validate the users token.
the query should return 0 rows if the token is invalid, or return a row where the first column has the IP:Port
Joe Huss